Volcarona
http://bulbapedia.bulbagarden.net/wiki/Volcarona_(Pok%C3%A9mon)
is a very powerful Fire/Bug type.
I am assuming this is black and white 2, you can find it when you get to driftviel. It's lv.35. Also, it's not a random wild pokemon, its a bit like a legendary, so you can reset till you get a good nature.
It learns Fly, so if you willing to give up a slot for a useless battle move on it, then it's good.
It's really good in game.
100 speed.
135 Sp.A
100 Sp.D
It covers your need for a fire type, and also it can learn fly. You can remove the HM after the elite four so you can give it another move.
Also it's OU in the Metagame.